Some attempts have so far been made to stably suspend water-insoluble calcium in water. Examples include a process which comprises treating calcium carbonate with a hydrophilic emulsifier (JP-B-2-31942 (the term "JP-B" as used herein means an "examined published Japanese patent publication")), a process which comprises stirring a slightly water soluble calcium salt together with an oxy acid, thereby obtaining the calcium salt having an average particle size of 1 .mu.m, and then adding a hydrophilic emulsifier to the resulting mixture (JP-A-8-107772 (the term "JP-A" as used herein means an "unexamined published Japanese patent application)), and a process which comprises treating a mixture of calcium carbonate and an emulsifier in a high-pressure homogenizer, thereby finely dispersing the mixture (JP-A-8-205820).
When the water-insoluble calcium salt is finely dispersed by any one of the above-exemplified processes, the sedimentation velocity becomes slow, but it sediments after allowed to stand for a certain time and forms a hard cake. Therefore, it is difficult to obtain a suspended state again.
JP-B-57-35945 and JP-B-63-29973 disclose a beverage which becomes free from the sedimentation of calcium due to the addition of crystalline cellulose. However, these techniques are accompanied by problems. For example, since the conventionally employed crystalline cellulose has a large particle size and the crystalline cellulose and calcium are not subjected to a co-grinding treatment, the effects of preventing sedimentation are not sufficient. In addition, a coarse texture is felt upon drinking the beverage.
An object of the present invention is to provide an aqueous suspension composition which is free from the sedimentation of the water-insoluble calcium material contained in the composition and which exhibits a stable dispersion state when added to foods, including a beverage, for the reinforcement of calcium or when added to coatings or the like as a filler. Another object of the present invention is to provide a preparation process for the aqueous suspension composition. Another object of the present invention is to provide a water-dispersible dry composition which permits re-dispersion of the water-insoluble calcium material and which exhibits a stable dispersion state without sedimentation by stirring in water.
Still another object of the present invention is to provide a food composition which has a water-insoluble calcium material stably dispersed therein by incorporating the aqueous suspension composition or the water-dispersible dry composition.